Ticks and the pathogens they transmit, including bacteria, viruses, protozoa, and helminths, constitute a growing burden for human and animal health worldwide. The ability of some animal species to acquire resistance to blood-feeding by ticks after a single or repeated infestation is known as acquired tick resistance (ATR). This resistance has been associated to tick-specific IgE response, the generation of skin-resident memory CD4 + T cells, basophil recruitment, histamine release, and epidermal hyperplasia. ATR has also been associated with protection to tick-borne tularemia through allergic klendusity, a disease-escaping ability produced by the development of hypersensitivity to an allergen. In addition to pathogen transmission, tick infestation in humans is associated with the α-Gal syndrome (AGS), a type of allergy characterized by an IgE response against the carbohydrate Galα1-3Gal (α-Gal). This glycan is present in tick salivary proteins and on the surface of tick-borne pathogens such as Borrelia burgdorferi and Anaplasma phagocytophilum , the causative agents of Lyme disease and granulocytic anaplasmosis. Most α-Gal-sensitized individuals develop IgE specific against this glycan, but only a small fraction develop the AGS. This review summarizes our current understanding of ATR and its impact on the continuum α-Gal sensitization, allergy, and the AGS. We propose that the α-Gal-specific IgE response in humans is an evolutionary adaptation associated with ATR and allergic klendusity with the trade-off of developing AGS.

A galactose-specific C-type lectin has been purified from a pupal extract of Drosophila melanogaster . This lectin gene, named DL1 ( D rosophila l ectin 1 ), is part of a gene cluster with the other two galactose-specific C-type lectin genes, named DL2 ( D rosophila l ectin 2 ) and DL3 ( D rosophila l ectin 3 ). These three genes are expressed differentially in fruit fly, but show similar haemagglutinating activities. The present study characterized the biochemical and biological properties of the DL1 protein. The recombinant DL1 protein bound to Escherichia coli and Erwinia chrysanthemi , but not to other Gram-negative or any other kinds of microbial strains that have been investigated. In addition, DL1 agglutinated E. coli and markedly intensified the association of a Drosophila haemocytes-derived cell line with E. coli . For in vivo genetic analysis of the lectin genes, we also established a null-mutant Drosophila . The induction of inducible antibacterial peptide genes was not impaired in the DL1 mutant, suggesting that the galactose-specific C-type lectin does not participate in the induction of antibacterial peptides, but possibly participates in the immune response via the haemocyte-mediated mechanism.

TGF-β (transforming growth factor-β) plays a critical role in modulating the inflammatory response and other biological processes through its regulation of the production of MMPs (matrix metalloproteinases). In both Mono-Mac-6 and RAW264.7 monocyte/macrophage cells, TGF-β abrogated lipopolysaccharide-induced increases in the enzymic activity and mRNA level of MMP-9. A fragment of the human MMP-9 promoter was used to characterize its regulation by TGF-β signalling. In RAW264.7 cells, TGF-β or its downstream signalling protein, Smad3 (Sma- and Mad-related protein 3), inhibited lipopolysaccharide-stimulated promoter activity. The suppressive activity of TGF-β on the MMP-9 promoter was abrogated by an inhibitory Smad, Smad7. The MMP-9 promoter contains a putative TIE (TGF-β inhibitory element). However, neither mutation nor deletion of the TIE had any effect on the inhibitory activity of TGF-β on MMP-9 transcription, indicating that the consensus TIE is not required for this effect of TGF-β. Analysis using a series of deletion mutants of the MMP-9 promoter revealed that a region containing a consensus NF-κB (nuclear factor-κB) site is required for the basal activity and TGF-β-mediated suppression of the promoter. Mutation of the putative NF-κB site not only markedly reduced the basal transcriptional activity of the promoter, but also abrogated the responsiveness of the promoter to TGF-β. In addition, a minimal promoter containing one copy of the NF-κB sequence was responsive to TGF-β treatment. Furthermore, an electrophoretic mobility shift assay was performed with the nuclear extracts from RAW264.7 cells, and it was found that TGF-β treatment did not disrupt the binding of NF-κB p50 and p65 proteins to the NF-κB sequence. Taken together, these studies indicate that the NF-κB site is indispensable for the suppressive activity of TGF-β in the regulation of MMP-9 transcription.